The present invention relates generally to the field of agricultural machinery, and more particularly to an apparatus for spreading pulverulent or granular material such as fertilizer, seeds, plant treatment agents and the like.
Numerous types of apparatus adapted to spread solid material are known operating in accordance with various principles, among which particular mention may be made of projection by purely mechanical means such as disks rotating at high speed, pneumatic means which entrain the material in a stream of air. Also known are devices which effect distribution via a conveyor member which may be a belt, a slide mechanism or a cylinder. In the devices which employ this second principle of operation, the material to be spread is fed by intermediate so-called feed means from a feed hopper to the distribution means.
The present invention relates more specifically to devices which operate in accordance with this second principle and more particularly to the type of devices in which the distributing member is a cylinder. In apparatus of this type, a shaft-mounted cylinder, which may be either ribbed, honeycombed or smooth, is generally a single part supported by a frame on its shaft ends, at one of which ends the rotary drive means is generally located. Moreover, the flow of the material to be spread takes place through a passageway provided between the lower part of an intermediate, so-called distribution hopper and the cylinder; this distance being variable in order to permit the passage of a smaller or larger amount of the material to be spread to thereby adjust the quantity of spread.
The assembly of arrangements referred to above implies a certain rigidity both of the hopper and of the cylinder, which rigidity arises from the thickness of these parts. It will be understood, therefore, that, due both to this thickness and to the shafts, their bearings and regulating means, the entire device possesses a substantial weight which limits its length.
Now it is clear that the operation of spreading over a given surface will be faster, the greater the width of the spreading strips; that is to say, the greater is the length of the spreading device. Thus the problem to which at the present invention is directed is the attainment of a maximum length for a given weight of the spreading device which is compatible with the supporting ability of the agricultural machines.